Comprehensive Overview of Phenolic Compounds: Phenylpropanoids, Benzenoids, Coumarins, and Tannins

[Music] [Music] welcome to nptl online certification

course on pharmacognosy and metabolic engineering this is lecture number 49 where I will talk talk about Phile

propanoid benzenoids kumarin and tannins this is basically I'll give you an overview in this

class so these are the concepts which are to be covered and let's let's go to the slide

so as I have mentioned before also that this is basically the Phile ring and the hydroxy group

which constitute the uh phenolic compound phenolic must for fulfill the this criteria but also I mentioned that

it is not always mandatory even the camic acids and then Phile ethanol these are also coming under phenolic because

it's it's originate from Phile alanin okay and some of the function of Phile propers I have mentioned in the

previous class uh so this one uh there is no point of discussing again uh and I ended the class with this

schematic diagram where I said that hydroxamic acid basically the p and these are different P1 P2 P3 P4 P5 say

P6 so many so on so on so that means that uh these are may be different uh transformation which includes hydroxy

methylation glucosylation chain clivage uh so many

okay and okay so this is again an overview which I have uh uh given in the previous

class so now come to here so this is called Phile proponent and phine proponent acetate skeletons so Phile

propon skeletons I have mentioned that which is basically C6 C3 and pine propon acetate

2 3 into C2 and C6 C3 this formed so and the this contributes this one is this acetate skeleton is coming from the uh

this melony atile derivatives and eventually it forms different phenolic

compounds okay like uh the flavonoids where it requires this like uh antoin so there the role of this acetate skeleton

is important and this is again a conifer alcohol which is which is a major constituent of the ligin

components uh so which is also called monol liol and this is a typical example of quatin as I said that this is

basically flavonoid so this is coming here whereas in case of Conifer alcohol which is where there is no involvement

of man manile derivatives so there there is no this orange structure is there so acetate origin is not required there so

now let us make an overview so what I have said that simate pathway contributes to phy alanin or tyosin or

both so the phy alanin are C6 C3 compounds I have shown the structure of phy alanin and then phy alanin by the

action of the enzyme phy alanine ammonia lies it converted into uh trinamic acid so this is phy

alanin ammonia lies which converts phy alanin into trans camic acid whereas the

tyrosin uh tyrosin this I draw in a different side

a different way but it is is all same so tyosin converted into for karic

acid this is called four or hydroxy camic

acid or for karic acid or even also it is called para karic

acid this is Ortho this is meta this is para so the enzyme here is called

T Phile alanin ammonia lies tyosin ammonia lies so which also released a molecule

of ammonia and makes paracolic acid so this T exists mostly in the monocot plants

because monocot plants are basically dominated by karic acids particularly the grasses so they are T exist it is

possible to measure the T from there okay and amino Amino oxy Phile propic acid so this is

basically act as an inhibitor so uh scientists they have studied

the pathway by feeding this so which basically act as an inhibitor of this

pal okay now go back to the yeah structure so this is pal pal makes either camic acid or okay yeah camic

acid and this enamic acid converted into subsequently into other simple phenolics Phile propanoids or

hydroxy camit so which are also C6 C3 compounds okay and uh as I also said that from tyrosin foric Acid which is

another hydroxy can be formed by the action of T but that is mostly confined to

the graming grass families okay next uh these simple uh camic acids will be converted

into the other hydroxycinnamic acids that is camic acid converted into paracom aric acid cafeic acid feric acid

uh all these things so these are all C6 C3 structures I will show you and uh now this C6 C3 structure what will

happen this will contribute towards the formation of lignin as I have mentioned this is the

lignin pathway uh and which is C6 C3 simple C6 C3 is monol liol but when that joins in

multiple numbers which form the polymer that is why this n is given here n so that is why it is called liin whereas

two such molecules form ligant okay now this C6 C3 structure joins with melony

qu either three molecules of melony ko or two molecules of Malon Co and it makes different structures which are

again C6 C3 C6 structure so this is chalone chalone is basically the precursor of antoin and the enzyme is

called chalone synthes so chalone synthes requires what is the substrate of chalon synthes one

is Malon qu three molecules of M koi and one molecule of parakum koi so the par Kumar

Royal qu plus 3 into malony KO makes chalone or we call

Tetra hydroxy chalon we will see this in details later the enzyme is called CHS similarly Malo qu joins with uh

Kumar KO and it makes another structure which is called steel bin so steel bin and uh chalone subsequently converted

into flavonoids uh so which are uh which constitute different classes like antoin

ponon uh uh isoflavones flavon so many things also C6 C3

structure uh joins together and form polymeric structure like subin cutin which basically deposits in the

epidermal cell layer and which uh protects the plant from different abiotic and biotic

stresses and again this C6 C3 C6 structure which I have shown here this contributes to the formation of

condensed tanins so where multiple of these units joins together and form this condens standing structure so you see

here the C6 C3 is the backbone from their different addition or substitution or chain shortening leads to the

formation of different compounds chain shortening is C6 C1 when you talk about C6 C1 then that is the example of chain

shortening like C6 uh C1 uh like benzenoids these are the

chain shorten compounds so uh I have mentioned this again in the again in the previous

class I mentioned this earlier in the previous class what is the chain shortening here yeah this is hydroxy

benzoid here and all other things I have already mentioned so let us now see so for of major phenolic groups from Phile

alanin and the core Phile proponent struct pathway so Phile alanin converted into trans camic acid by the action of

the enzyme pal this is pal and uh that trans camic acid contributes directly towards formation of benzenoid compounds

that is why benzoic acid derivatives is written here and trinamic acid by the action of one hydroxy it forms this uh

four hydroxy camic acid uh which is also called parakum aric acid I have drawn the structure just before so this is a

Hydrox silation added at the fourth position that means this is uh

uh 1 2 3 4 5 6 okay and then uh so this parakum aric acid contributes to the formation of

cafeic acid ferulic acid Aid and other important Phile propanoid structure and this parakum aric acid

also under goes activation this is called activation of hydroxamic acids where uh qu molecule

joints uh qu molecule joins so and by the action of an enzyme called comar Co lias or for hydroxy Co lias so lias mean

addition of qu molecule which requires ATP and mgcl2 uh to perform its function and it

forms the paracom oil qu so pararel KO is a very active molecule because it takes part into different components

such as ligin precursors such as steel bins such as kumarin and of course for the flavonoids

and anthos sinins so paracom qu is a very it's called activated hydroxy camet because a qu molecule is added and then

upon joining with malony qu I have mentioned just in the pre in the previous slide it forms the chalone and

from chalone it forms different flavonoid structures so tell so this is the structure of hydroxycinnamic acid so

like uh this is the trans camic acid which converted into by the action of c4h uh cam 4 hydroxy camate 4 hydroxy

which makes a four position o added so this structure is called four hydroxycinnamic acid or parakum aric

acid or for karic acid all are correct and then we'll also

see ideally from for karic acid if what will happen first a hydroxy will add here

and in so that is the job of the hydroxy and the next job will be that this will be replaced

by methy group so and eventually this structure is this one which is called ferulic acid or you can say four hydroxy

three methoxy camic acid for four hydroxy 3 methoxy camic acid or it is called ferulic

acid uh although the formation of ferulic acid is not straightforward in this way which we'll see later but

theoretically feric acid can be formed from parakum Maric acid by entic steps farther will be Hydrox silation then

there will be methy transference uh so where which requires a methy group donut like Sam and which makes ferulic acid

and feric acid subsequently again undergo Hydrox silation at five position this is four position this is

five position this is three position so and then uh this is for hydroxy and then there will be that will methylated So

methoxy eventually so this is called uh Copic acid s n p i Copic acid or four hydroxy

3 5 dioxy camic acid or four hydroxy 35 dioxy uh camic acid these are the different

names now hydroxy Camile alcohols this we'll discuss again when we'll talk about the monol liol

biosynthesis in next class but briefly paric acid is converted into paracom oil qu

this is activation of hydroxy then what will happen there will be a reductor activity so this enzyme is called forcl

this enzyme is called reductor CCR Camile Co reductors and relates to the formation

of this structure this is Camal deide or karal deide sorry karal deide and then Kumar

alide again there will be the action of CAD alcohol dehydrogen and which eventually form the

Kumar alcohol or parar alcohol also you can say uh and and uh this constitutes one of

the units of the ligin monomer so this is called monol liol similarly uh from ferulic Acid another

monolignol structure orus which is conifer alcohol from Copic acid another monolignol structure oers which is is

called copile alcohol so detail of this I will talk in the subsequent class now kumarin kumarin are also important

molecules so kumarin basically they act as a defense compound and they basically formed uh from the karic acid is the

basic structure uh so uh uh and then it forms uh for example karic acid then karic acid ultimately it forms Ameron

which is seven hydroxy kumarin and then you'll get a compound called sorin which is not good for health because if you

touch in the skin it form blisters and karic acid converted into ferulic acid and subsequently the ferulic acid by the

action of uh feret uh uh six Prime hydroxy uh so at the six Prime hydroxy

is so 1 2 2 3 4 5 6 at this position 65 hydroxy is it eventually forms this

structure scopoletin so this is one example of uh hydroxy komarin uh so here is the structure of selin which is

coming through the Ameron okay so and this is a general skeleton of the

kumarin structure and uh a linear f rumarin which is eight myoxy oralin synthesizes human skin to UV a light uh

so this compound present in this plant uh and cause severe blistering on skin followed by exposure to UV IR radiation

so this is huran kumarin and you see the blisters now come to the condensed tanins okay condensed tanins

basically are formed uh by joining of this uh C6 C3 C6 in multiple numbers okay the first one is called the uh

where n equal to 1 to 10 when when when n equal to 1 to 10 so it it also contains three hydroxy group so this is

basically the structure of the condens standings and the hydroxy group of a hexos are esterified with the GIC acid

and here the bottom one is the hydrolyzable tanins which is basically originate from

the GIC acid and uh yeah so this is uh condensed tannins you find in different

plants uh like hokis Baha these plants you will find tenants so this is again another example of this uh hydrolyzable

tenin uh which is found in the chest knot castal again this is the name of this and

uh one example of this I have put it okay so this is again um gallic acid

uh so so this is basically the gluc galine is the EST form of GIC acid and this finally forms this gallic acid um

this condens tanins now biosynthesis of benzenoids as I mentioned that benzenoids are C6 C1

compound so basically it forms from C6 C3 structure by a chain cage so cleage means that

the it basically Clips out the C2 so there are the Phile alanin which makes trans camic acid as I have

mentioned by this by the action of the pal and then by for cl it makes Camile KO and what happens the trans camic

acid can take part in the formation of benzal deide when you talk about the benzal deide if you see this structure

this is C6 C1 structure this is C1 right okay so uh what happens from stomic Acid it can directly from benzal

deide which is called qu independent non beta oxidative root qu independent qu independent so

that means there is no involvement of qu here and this is a non beta oxidative or non oxida root which how it happens that

there will be the formation of inter one intermediate which is called beta hydroxy Phile propic acid and uh and

there will be maybe the enzyme is called benzal deide synthes this mostly is unstable compounds and eventually it

makes benzal deide and benzal deide contributes to the benzoic acid so this is one root so similar root also exist

for hydroxy uh benzo molecule as as well uh we will discuss sometime later and on so this is one root the root number two

is basically qu dependent bet oxidative root where Camile qu forms beta hydroxy

Phile propano qu and then beta oxop propano qu and then it forms the benzo qu

so so here so here it involves different enzymes for example uh phen beta hydroxy

Phile propano qu so that from Camile Co Camile Co this is forcl there is another enzyme called CNL so

CNL is that basically a specific enzyme which contributes towards the formation of this Benz structure here there is

called Camile Co iess but this is term as CNL uh so normally the 4cl is used for

Activation of hydroxy camit when there is no hydroxy only cinet so there CNL terminology is used uh and it forms the

three hydroxy uh this three Phile propanol qu and then it makes beta oopen propano qu and then finally it makes

benzo qu so Enzo qu when it forms so there is an enzyme called keto asile cooles this one this is called K

A K is a recently discovered enzyme keto asile three keto asile

okay qu thyes t h i o l a thol means basically the uh removal of

the it's a th AC removal of the qu thester and that leads to the formation of the benzo qu and benzo qu

subsequently forms the benzoic acid and uh and uh then and this benzoic acid May

contribute towards the formation of salicylic acid because uh if this is one position this is two so if I hydroxy

added then it becomes salicylic acid so long back one work from rgar University they mention about this IL

raskins group but later it was found that that may be existed but mostly uh the salicylic acid is formed from

chorismic Acid by isochorismate synthes which makes isocoric acid then there will be isocor

pyet lies which basically release the pyic acid and produces the saltic acid and this is the most acceptable uh root

of uh salicylic acid so salicylate is also a benzenoid because this is C6 C6 C1

structure maneline is also C6 C1 structure so so what we see here that the core

Phile propanoid pathway uh which is contributes towards the formation of Kumar KO and malony qu and

by the action of chalone synes it forms chalone and subsequently the pathway contributes towards the flavonol the

pathway also contributes towards the antoin uh the pathway also contributes towards the unusual pigment flowen maybe

I will discuss all these things in due course and flavones and also that that this

chalones can take part in the formation of isop flavons which are basically dominant in the

legumes so this is basically the pathways and Branch points leading to the formation of major flavonoid groups

and related compounds like isoflavones isoflavonoids anthocyanin and then proanthocyanidin that is condens tanins

uh which also form from this way so like this joints together and and also steel bin steel ban we'll see now so steel ban

and chalone so what happens there is an enzyme called steelan

synthes okay which requires again three molecules of Mal qu plus qu and which what will happens it liberates four qu

Harvesters and carbon dioxide leading to the formation of a steel bin structure which is called Resveratrol resol is an

strong antioxidant and it it basically accumulates in the red grips therefore consuming red wine is good because it

contains Resveratrol which gives protection to heart diseases but resveratol is produced grape basical it

is act as a defense compound particularly it gives protection against fungal diseases okay in another complex

structure of this uh steel bin is viniferin which is also found in this so This basically act as an antifungal

compound so later this structure has been synthesized and it is used as fite but originally it is basically found in

on P species uh the same malony KO and karile KO

also contributes towards the formation of chalone by the action of chalone synthes so this is the structure of

tetrah hydroxy chalone as you see this this red one is basically coming from the acetate unit okay acetate malony

unit and whereas this one one is coming from the Kumar unit the black one and shalone is the precursor of

various flavonoids uh like I have mentioned flavonones flavons isoflavones flavonols

anthocyanin and uh this is typically the structure of uh flavonone and flavon 3 alls and flavons maybe I will in one of

the classes I will draw this structure uh to explain the differences between this whatever required I'll not go to

that much complex way but whatever required I will discuss this so isop flavons as I mentioned this is found in

the legumes and genine one such isop flavons and these are all dietary phenolic compounds so this is very

important for health purpose and then uh similarly this malony qu and this paracom KO or mile KO with cinile KO or

M KO with C KO that means man KO joins with cinam KO or it joins with paracom KO or even it joins

with Cil Co and forms different structure like benile acetones

like aril Pyon aril Pyon so one good example is Hyo

sooin is found in the Primitive uh thopi cotum so you you see that it originates

from this pathway and I have mentioned about scotin and when I talk about the evolution of this metabolic pathways

maybe again I will I will discuss that when I talk about the xanthon and so this is Comm under AR

Pyon then similarly styop pyrons are produced uh his is one example and chalon of course steel bins are example

and the example of the steel bins one is the resveratol other is Pino silvin Pino silvin is another example of

Steel bin uh Shalon naringenin R diol so these are all examples so this is basically the

designation of 1x 2x 3x refers to the number of mol equivalent units of Mile qu when whatever number is required for

example uh in formation of styop Pyon require two molecu Mar whereas cinin or aril Pyon require one molecule whereas

tilin and chalone requires three molecules of Alon qu so this is what it is about so and then uh this

eventually uh forms different complex uh flavonoid subclasses uh so this all looks very

Greek so I will not really discuss in details but the example you must uh know a little bit diin is one isoflavonoid

which is uh there in legumes similarly medicarpin which is is a phyto alexin sort of compound so that gives

protection to plant against pathogen attack uh ninenine contributes towards the formation of

antoin uh like uh this is an Aon Aon is also contributing to the pigments like in

Cana Kaa species uh so that that the pigment is basically originates from the Aon so these are the some of the

examples of different flavonoid classes so with this I end this class so I have given you brief overview of the Phile

propanoids benzenoids condensed tannins and and steel bins and little bit of flavonoids here so I hope you

understand and you have enjoyed so see you again in the next class thank you very

much